Solenoid valve

ABSTRACT

A solenoid valve ( 10 ) has a U-shaped fixed iron core ( 50 ) with a driving leg ( 51 ), a supporting leg ( 52 ), and a yoke portion ( 53 ) integrally formed. One end portion of a movable iron core ( 60 ) which drives a poppet valve ( 41 ) abuts on the supporting leg ( 52 ), and the other end portion of the movable iron core ( 60 ) abuts on the driving leg ( 51 ). A sealing member ( 81 ) is disposed between and a valve housing ( 11 ) and a fixed flange ( 58 ) of a bobbin ( 54 ) attached to the fixed iron core ( 50 ). A sealing member ( 83 ) is disposed between an abutting flange ( 57 ) of the bobbin ( 54 ) and the yoke portion ( 53 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application of International PatentApplication No. PCT/JP2015/061480, filed on Apr. 14, 2015, which claimspriority to Japanese Patent Application No. 2014-167722, filed on Aug.20, 2014, each of which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

The present invention relates to a solenoid valve which uses a poppetvalve to open and close a communication hole in a valve seat.

BACKGROUND ART

To control supplying of compressed air to a pneumatic equipment or thelike, or to control compressed air exhaust from the pneumatic equipment,or further to control a process to switch communication passages, asolenoid valve which uses a poppet valve to open and close communicationholes provided in a valve seat has been utilized.

In a two-port solenoid valve having an air-supply port communicatingwith a compressed air-supply source and an output port communicatingwith an equipment to be supplied with compressed air, a poppet valvecontrols switching between a communicating state and a blocked state ofthe ports. On the other hand, in a three-port solenoid valve having anexhaust port in addition to the air-supply port and the output port, thepoppet valve controls switching between two states. In one state, thepoppet valve operates to block communication between the exhaust portand the output port while enabling communication between the air-supplyport and the output port, thereby supplying compressed air to thepneumatic equipment through the output port. In the other state, thepoppet valve operates to block communication between the air-supply portand the output port while enabling communication between the exhaustport and the output port, thereby discharging the compressed air, whichreturned to the output port from the pneumatic equipment, to the outsidethrough the exhaust port.

A solenoid which opens and closes the poppet valve has a fixed iron corewith a magnetic wire wound around, and a movable iron core to be drivenby the magnetic wire, that is, an energized coil; thus, a poppet valveis driven by the movable iron core. The movable iron core is a swingabletype which is swingable about one end portion of the movable iron core;this swingable movable iron core is also referred to as a “flapper” oran “armature”. Japanese Unexamined Utility Model Application PublicationNo. H03-020405 and Japanese Unexamined Patent Application PublicationNo. H08-330130 describe such solenoid valves each having a swingablemovable iron core.

SUMMARY

The solenoid valve described in Japanese Unexamined Utility ModelApplication Publication No. H03-020405 has a straight fixed iron core,and a base end portion of the fixed iron core is attached with anL-shaped yoke; the yoke is fitted to a small-diameter portion formed onthe base end portion of the fixed iron core. A movable iron core whichdrives a valve element is disposed along a leading end of the fixed ironcore and extends to a leading end of the yoke, one end portion of themovable iron core abutting on the leading end of the yoke so that themovable iron core is swingable about the one end portion abutting on theyoke. When a coil wound around the movable iron core is energized, amagnetic circuit is generated between the fixed iron core, the yoke andthe movable iron core, so that the other end portion of the movable ironcore is attracted onto a magnetically-attracting surface provided on aleading end of the movable iron core.

The solenoid valve described in Japanese Unexamined Patent ApplicationPublication No. H08-330130 is provided with a fixed iron core having ashaft and a large-diameter magnetically-attracting portion, themagnetically-attracting portion being provided on a leading end of theshaft. A magnetic frame which is L-shaped in cross-section is attachedto a base end portion of the fixed iron core. A flapper, that is, amovable iron core, which drives a poppet valve is disposed along aleading end of the magnetically-attracting portion of the fixed ironcore and extends to a leading end of the magnetic frame. One end portionof the flapper abuts on and is fixed onto the leading end of themagnetic frame, and the movable iron core is swingable about the one endportion of the movable iron core abutting on the magnetic frame. When acoil wound around the fixed iron core is energized, a magnetic circuitis generated between the fixed iron core, the magnetic frame and theflapper, so that the other end portion of the flapper is attracted ontothe magnetically-attracting portion of the fixed iron core.

The fixed iron core described in Japanese Unexamined Utility ModelApplication Publication No. H03-020405 and Japanese Unexamined PatentApplication Publication No. H08-330130 comprises two parts, such as thefixed iron core and the yoke, to generate the magnetic circuit with themovable iron core; thus, the number of steps to assemble the solenoidvalve increases and the solenoid valve cannot be reduced in size.

As described in Japanese Unexamined Patent Application Publication No.H08-330130, to fix the magnetic frame, the fixed iron core, and the coilinto a case by using resin, a valve housing needs two members, that is,a coil case and a body to store a poppet valve, and resin needs beinjected into the case prior to attaching the body to the case. Inaddition, although the fixed iron core and the yoke, or the magneticframe, are fixed by resin, a gap between the fixed iron core and thebobbin needs to be sealed to prevent compressed air from leaking to theoutside of the solenoid valve.

An object of the present invention is to reduce the size of the solenoidvalve by cutting down the number of parts composing the solenoid valve.

A solenoid valve according to one aspect of the present inventioncomprises a poppet valve which is operated between: a closed position inwhich the poppet valve abuts on a valve seat to block communicationamong ports; and an open position in which the poppet valve separatesfrom the valve seat to enable communication among the ports, thesolenoid valve having: a valve housing which is provided with the portsand in which the poppet valve is assembled; a fixed iron core which isassembled into the valve housing and is provided with: a supporting legabutting on one end portion of a movable iron core which drives thepoppet valve; a driving leg extending in parallel to the supporting legand abutting on the other end portion of the movable iron core; and ayoke portion provided between a base end portion of the supporting legand a base end portion of the driving leg; the supporting leg, thedriving leg, and the yoke portion being integrally formed; and a coilprovided on the fixed iron core.

The fixed iron core has a structure in which the driving leg, thesupporting leg and the yoke portion are integrally formed with eachother; thus, the number of parts of the solenoid valve can be reduced incomparison to the fixed iron core which is composed by a plurality ofparts. Therefore, the solenoid valve can be reduced in size, andassembly workability of the solenoid valve can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a solenoid valve according toan embodiment of the present invention with the coil de-energized;

FIG. 2 is a cross-sectional view showing the solenoid valve of FIG. 1with the coil energized;

FIG. 3 is an exploded perspective view showing the solenoid valve ofFIGS. 1 and 2;

FIG. 4 is an enlarged perspective view showing a spring member of FIG.3;

FIG. 5 is an enlarged perspective view showing a valve driving member ofFIG. 3;

FIG. 6 is an enlarged perspective view showing a fixed iron core of FIG.3;

FIG. 7A is an enlarged cross-sectional view taken along a line 7A-7A ofFIG. 1;

FIG. 7B is an enlarged cross-sectional view taken along a line 7B-7B ofFIG. 1;

FIG. 8 is an enlarged cross-sectional view showing one portion of FIG. 2with a flow passage block omitted;

FIG. 9 is a cross-sectional view showing a variation of the solenoidvalve;

FIG. 10A is an enlarged cross-sectional view taken along a line 10A-10Aof FIG. 9;

FIG. 10B is an enlarged cross-sectional view taken along a line 10B-10Bof FIG. 9;

FIG. 11 is a cross-sectional view showing another variation of thesolenoid valve; and

FIG. 12 is a cross-sectional view showing yet another variation of thesolenoid valve.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present invention will be described indetail on the basis of the drawings. As shown in FIGS. 1 to 3, asolenoid valve 10 has a valve housing 11 made of resin. As shown in FIG.3, the valve housing 11 has a front wall 12, a rear wall 13 and sidewalls 14 and 15, and is substantially rectangular in shape. As shown inFIGS. 1 and 2, one end portion of the valve housing 11 in a longitudinaldirection is provided with a flow passage portion 16, and the other endportion is indicated as an opening end 17. In this manner, the valvehousing 11 has four walls which form a quadrilateral shape in across-sectional view of the valve housing 11, and a bottom portion ofthe valve housing 11 is closed by the flow passage portion 16. A housingspace 18 is provided in the valve housing 11, and parts constituting thesolenoid valve 10 are stored in the housing space 18.

The flow passage portion 16 is provided with a first port 21, a secondport 22 and a third port 23; thus, the solenoid valve 10 is a three-portsolenoid valve. The ports 21 to 23 extend through the valve housing 11in a front to rear direction, and are adjacently opened on a same sideas the rear wall 13 of the valve housing 11. The second port 22 ispositioned closer to the opening end 17 than the first port 21, and thethird port 23 is positioned closer to the opening end 17 than the secondport 22.

The flow passage portion 16 is provided with a first valve seat 24 onthe front wall 12. The first valve seat 24 is provided with a firstcommunication hole 25 which communicates with the first port 21, thefirst communication hole 25 extending in the longitudinal direction ofthe valve housing 11. The flow passage portion 16 of the valve housing11 is provided with a valve element housing hole 26; the firstcommunication hole 25 extends to a bottom portion of the valve elementhousing hole 26, and the second port 22 extends to an innercircumferential surface of the valve element housing hole 26. Thus, thefirst port 21 is communicated with the second port 22 through the firstcommunication hole 25 and the valve element housing hole 26.

A flow passage block 27 is inserted into the valve housing 11 from theopening end 17 of the valve housing 11. As shown in FIG. 7, the flowpassage block 27 is assembled into the valve housing 11 so that a bottomsurface of the flow passage block 27 abuts on an abutting surface 16 aprovided on the flow passage portion 16. The flow passage block 27partially constitutes the valve housing 11. The flow passage block 27partitions the valve element housing hole 26 into a space on a same sideas the opening end 17 and a space in the bottom portion of the valveelement housing hole 26. The flow passage block 27 abuts on the abuttingsurface 16 a; thus, the flow passage block 27 is correctly positioned.

The flow passage portion 16 is provided with a fitting hole 28 betweenthe second port 22 and the third port 23. Additionally, the flow passageportion 16 is provided with a fitting hole 29 which is positioned closerto the opening end 17 than the third port 23. Each fitting hole 28 and29 has an inner circumferential surface which is substantiallyquadrilateral in shape. The flow passage block 27 has: a first flowpassage forming portion 31 which is fitted into the fitting hole 28; asecond flow passage forming portion 32 which is fitted into the fittinghole 29; and a spacer 33 which is provided between the flow passageforming portions 31 and 32. The two flow passage forming portions 31 and32 and the spacer 33 are integrally molded and are made of resin.

A second valve seat 34 is provided on the first flow passage formingportion 31 so as to face the first valve seat 24. The second valve seat34 is provided with a second communication hole 35 which is coaxial withthe first communication hole 25, and the second communication hole 35extends to the valve element housing hole 26. The spacer 33 of the flowpassage block 27 is provided with a communication passage 36 throughwhich the second communication hole 35 and the third port 23 communicatewith each other. Thus, the second port 22 is communicated with the thirdport 23 through the valve element housing hole 26, the secondcommunication hole 35 and the communication passage 36. A sealing member37 seals a gap between the first flow passage forming portion 31 of theflow passage block 27 and the valve housing 11. A sealing member 38seals a gap between the second flow passage forming portion 32 and thevalve housing 11.

A poppet valve 41, which is a valve element made of rubber, is stored inthe valve element housing hole 26. A valve driving member 42 is made ofmetal or resin and has a cylindrical portion 43; the poppet valve 41 isinserted and attached to the cylindrical portion 43 from its bottomside. As shown in FIGS. 3 and 5, the valve driving member 42 has twodriving portions 44 which are integrated with the cylindrical portion43. The driving portions 44 are inserted into two through holes 45provided on the flow passage block 27, and are axially movable. Anarcuate surface is formed on each tip portion 44 a of the drivingportions 44, and as shown in FIG. 8, the tip portions 44 a protrude fromthe flow passage block 27 toward the opening end 17 of the valve housing11.

The valve element housing hole 26, in which the poppet valve 41 and thecylindrical portion 43 are stored, extends toward the opening end 17 ofthe valve housing 11 through the fitting holes 28 and 29. Thus, thedriving portions 44 are inserted into the through holes 45 prior to thevalve driving member 42 and the flow passage block 27 being insertedinto the valve housing 11 from the same side as the opening end 17. Inthis manner, the valve driving member 42 and the flow passage block 27are assembled into the flow passage portion 16, and the poppet valve 41is disposed in the valve element housing hole 26.

The poppet valve 41 has two end surfaces which abut on the valve seats24 and 34. As shown in FIG. 1, when the poppet valve 41 separates fromthe second valve seat 34 to abut on the first valve seat 24, the poppetvalve 41 closes the first communication hole 25 and is set to a closedposition to block communication between the first port 21 and the secondport 22, while further being set to an open position to allow the secondport 22 and the third port 23 to communicate with each other. On theother hand, as shown in FIG. 2, when the poppet valve 41 separates fromthe first valve seat 24 to abut on the second valve seat 34, the poppetvalve 41 closes the second communication hole 35 and is set in an openposition to allow the first port 21 and the second port 22 tocommunicate with each other, while being further set to a closedposition to block communication between the second port 22 and the thirdport 23. In this manner, the poppet valve 41 is operated between aposition to abut on the first valve seat 24 to close the firstcommunication hole 25, and a position to abut on the second valve seat34 to close the second communication hole 35. A compression spring 46,which serves as a spring member, is installed between the poppet valve41 and the flow passage portion 16. By a spring force of thiscompression spring 46, the poppet valve 41 is urged in a directiontoward the second valve seat 34.

A fixed iron core 50 made of magnetic material is provided in the valvehousing 11. As shown in FIGS. 3 and 6, the fixed iron core 50 has adriving leg 51 and a supporting leg 52 which extend in parallel witheach other, and the fixed iron core 50 is provided in the valve housing11 with the driving leg 51 and the supporting leg 52 extending along alongitudinal direction of the valve housing 11. Base end portions of thedriving leg 51 and the supporting leg 52 are integrally joined by a yokeportion 53; thus, the fixed iron core 50 has a U-shape. In this manner,the driving leg 51, the supporting leg 52 and the yoke portion 53integrally constitutes the fixed iron core 50. Therefore, in comparisonto a fixed iron core composed of two parts, the number of parts of thefixed iron core 50 can be reduced to one, thereby reducing the number ofparts of the solenoid valve 10; hence, the solenoid valve 10 can bereduced in size and assembly workability can be enhanced. The drivingleg 51, the supporting leg 52 and the yoke portion 53 each have aquadrilateral shape in a cross-sectional view. As shown in FIG. 6, awidth dimension W1 of the supporting leg 52 is larger than a widthdimension W2 of the driving leg 51, and a width dimension of the yokeportion 53 is substantially equal to the width dimension of thesupporting leg 52.

In addition, a sealing flange 78 having a depth dimension larger than adepth dimension of the supporting leg 52 is provided on a leading endportion of the supporting leg 52. Furthermore, an abutting protrusion 67is provided closer to the leading end portion of the supporting leg 52than the sealing flange 78. In other words, the abutting protrusion 67is formed on the supporting leg 52 and is positioned closer to theleading end portion than the sealing flange 78. As shown in FIG. 6, thewidth dimension W1 of the supporting leg 52 is equal to the widthdimension of the yoke portion 53 and the sealing flange 78. In contrast,the width dimension W2 of the driving leg 51 is smaller than the widthdimension W1 of the supporting leg 52. In the same manner, a widthdimension W3 of the abutting protrusion 67 is smaller than the widthdimension W1 of the supporting leg 52. Additionally, a depth dimensionD2 of the abutting protrusion 67 is smaller than a depth dimension D1 ofthe sealing flange 78. Thus, a sealing surface which surrounds theabutting protrusion 67 is formed on a side of the sealing flange 78facing the flow passage block 27. Moreover, a sealing surface whichsurrounds the driving leg 51 is formed on a side of the yoke portion 53facing the flow passage block 27.

The fixed iron core 50 is attached with a bobbin 54 made of resin. Thebobbin 54 has a cylindrical main body 55 through which the driving leg51 is inserted; a magnetic wire is wound around an outside of thecylindrical main body 55 and forms a coil 56. One end of the cylindricalmain body 55 is provided with an abutting flange 57 which abuts on aninner surface of the yoke portion 53, and the abutting flange 57 isintegrated with the cylindrical main body 55. The other end of thecylindrical main body 55 is provided with a fixed flange 58 which isfitted into an inner surface of the valve housing 11, and the fixedflange 58 is integrated with the cylindrical main body 55. A drivingprotrusion 66 on a leading end portion of the driving leg 51 and theabutting protrusion 67 on the leading end portion of the supporting leg52 protrude from the fixed flange 58 toward the flow passage block 27.

The fixed flange 58 is provided with a fitting protrusion 77 on its endsurface, and a first sealing member 81 is hermetically fitted on anoutside of the fitting protrusion 77. The abutting protrusion 67 whichis on the leading end portion of the supporting leg 52 is provided withthe sealing flange 78, and the sealing flange 78 surrounds the abuttingprotrusion 67. A second sealing member 82 is hermetically fitted betweenthe sealing flange 78 and the fixed flange 58. Moreover, a sealingmember 83 is hermetically fitted around the driving leg 51, between theabutting flange 57 and the yoke portion 53. The first sealing member 81seals a gap between the fitting protrusion 77 of the fixed flange 58 andthe inner surface of the valve housing 11, and the second sealing member82 which is set in a concave groove formed on an inner surface of thefixed flange 58 seals a gap between an end surface of the sealing flange78 and the fixed flange 58. Moreover, the sealing member 83 which is setin a groove formed on an inner surface of the abutting flange 57 seals asealing surface formed between the yoke portion 53 and the abuttingflange 57.

When the second sealing member 82 is fitted on a sealing surface of theabutting protrusion 67, and the sealing member 83 is fitted on a sealingsurface at a base end portion of the driving leg 51, the sealing members82 and 83 are prevented from falling out of the fixed iron core 50.Thus, assembly can be easily achieved by respectively attaching thesealing members 82 and 83 to the sealing surfaces prior to inserting thefixed iron core 50 into the bobbin 54.

An iron core housing 59 is provided between the fixed flange 58 and theflow passage block 27, and a movable iron core 60 is installed in theiron core housing chamber 59. As shown in FIGS. 1 and 2, the movableiron core 60 is disposed between the leading end portion of the drivingleg 51 and the leading end portion of the supporting leg 52, that is,along the leading end portions of the fixed iron core 50. An arcuatesliding-contacting surface 61, which has a curve extending along alongitudinal direction of the movable iron core 60, is provided on oneend portion of the movable iron core 60. An arcuate sliding-abuttingsurface 62 is provided on the leading end portion of the supporting leg52 and corresponds to the sliding-contacting surface 61. Thesliding-contacting surface 61 of the movable iron core 60 abuts on thesliding-abutting surface 62 of the supporting leg 52 so that the movableiron core 60 is swingable about one end portion of the sliding-abuttingsurface 62. The sliding-contacting surface 61 has a concave surface, andas shown in FIG. 3, the sliding-contacting surface 61 linearly extendsin a width direction of the movable iron core 60. Moreover, thesliding-abutting surface 62 has a convex surface, and as shown in FIGS.3 and 6, the sliding-abutting surface 62 linearly extends in a widthdirection of the supporting leg 52. The movable iron core 60 isswingable about a center point of the arcuate convex surface of thesliding-abutting surface 62.

In this manner, one end portion of the movable iron core 60 abuts on thesupporting leg 52 and corresponds to a swinging center of the swingingmovements. The other end portion of the movable iron core 60 serves as aswingable end in which the movable iron core 60 swings between aposition to abut on the driving leg 51 and a position to separate fromthe driving leg 51. The sliding-contacting surface 61 is provided on themovable iron core 60, and the sliding-contacting surface 61 abuts on thearcuate sliding-abutting surface 62 which is provided on the leading endportion of the supporting leg 52. Therefore, the movable iron core 60 isswingable without shaft members or the like fixing the movable iron core60 onto the supporting leg 52. This structure does not require any typeof shaft member, thereby reducing the number of parts of the solenoidvalve 10; hence, the solenoid valve 10 can be reduced in size and caneasily be assembled. Moreover, the movable iron core 60 has no need toutilize members to secure a swinging center since the swinging center ofthe movable iron core 60 is always maintained at the same position;thus, the opening and closing precision of the poppet valve can bemaintained. In a variation in which the sliding-contacting surface 61has a convex surface and the sliding-abutting surface 62 has a concavesurface, the movable iron core 60 is swingable about a center point ofthe arcuate convex surface of the sliding-contacting surface 61.

A magnetically-attracting surface 63 is provided on an end surface ofthe driving leg 51, and a magnetically-attracted surface 64 is providedon the other end portion of the movable iron core 60. Themagnetically-attracted surface 64 faces the magnetically-attractingsurface 63; the magnetically-attracted surface 64 is formed into aconcave groove 65 which has a V-shape in the longitudinal direction ofthe movable iron core 60. The magnetically-attracting surface 63 isformed by the V-shaped driving protrusion 66 which is pushed into theconcave groove 65. In this manner, when the magnetically-attractingsurface 63 and the magnetically-attracted surface 64 are formed intoV-shapes, the respective areas are larger than that of a flat surface,and the movable iron core can be prevented from becoming larger in size.When the magnetically-attracting surface 63 and themagnetically-attracted surface 64 are respectively formed into arcuatesurfaces in the same manner as in the sliding-contacting surface 61 andthe sliding-abutting surface 62, the respective areas are larger in thesame manner.

The sliding-contacting surface 61 and the magnetically-attracted surface64 of the movable iron core 60 are provided on a surface, that is, aniron core facing surface 60 a, so as to face the fixed iron core 50;thus, the iron core facing surface 60 a faces the opening end 17 of thevalve housing 11.

A flat spring 70, which is made of steel and serves as a spring member,is provided in the iron core housing chamber 59. The flat spring 70 ispositioned between the movable iron core 60 and the flow passage block27. As shown in FIGS. 3 and 4, the flat spring 70 has two supportingportions 71. The movable iron core 60 has the iron core facing surface60 a and a bottom surface, that is, a valve driving surface 60 b, whichis on an opposite side relative to the iron core facing surface 60 a.The two supporting portions 71 of the flat spring 70 extend along thevalve driving surface 60 b. The supporting portions 71 respectivelyextend to side surfaces of the movable iron core 60 along the valvedriving surface 60 b, and an attaching claw 72 is provided on eachsupporting portion 71. As shown in FIG. 3, attaching claw holders 95 areprovided on two separate locations at a bottom portion of the fixedflange 58 of the bobbin 54. Each attaching claw 72 of the flat spring 70is respectively engaged with an attaching claw holder 95 on the bobbin54. A pulling portion 73 is provided between the two supporting portions71, and extends along the supporting portions 71; a base end portion ofthe pulling portion 73 and base end portions of each supporting portion71 are integrated with a connected portion 74. The pulling portion 73extends along the valve driving surface 60 b of the movable iron core60. An engaging protrusion 76 is provided on the swingable end of themovable iron core 60. An engaging claw 75 which is engaged with theengaging protrusion 76 of the movable iron core 60 is provided on theend portion of the pulling portion 73.

In this manner, the pulling portion 73 of the flat spring 70 for thesolenoid valve extends from the connected portion 74, which faces oneend portion of the movable iron core 60, to the side which faces theswingable end of the movable iron core 60. Moreover, the supportingportions 71 are provided on both sides of the pulling portion 73, andextend from the connected portion 74 toward a side facing the swingableend of the movable iron core 60.

The movable iron core 60 is attached to the flat spring 70 by theengagement between the engaging protrusion 76 and the engaging claw 75of the flat spring 70. Moreover, the flat spring 70 to which the movableiron core 60 is attached is further attached to the bobbin 54 by therespective engagements between the attaching claws 72 of the flat spring70 and the attaching claw holders 95 of the bobbin 54. In this manner,the movable iron core 60, the flat spring 70 and the bobbin 54 aretemporarily assembled by these engagements, and the flat spring 70 isfixed by being sandwiched between the bobbin 54 and the flow passageblock 27 which constitutes one portion of the valve housing 11. Thepulling portion 73 has a spring force in a direction separating from themovable iron core 60, that is, in a direction toward the flow passageblock 27, and the spring force is stronger than that of the supportingportions 71. Therefore, the flat spring 70 applies two forces to themovable iron core 60. One force presses the sliding-contacting surface61 at one end portion of the movable iron core 60 onto thesliding-abutting surface 62 of the supporting leg 52, and the otherforce is exerted in a direction to separate the magnetically-attractedsurface 64 of the other end portion of the movable iron core 60 from themagnetically-attracting surface 63 of the driving leg 51.

In this manner, the spring force of the flat spring 70 urges the poppetvalve 41 in a direction toward the first valve seat 24. With theexception of the engaging claw 75 and attaching claws 72, flat portionsof the flat spring 70 are disposed in a gap between the valve drivingsurface 60 b of the movable iron core 60 and the flow passage block 27.Therefore, the space for storing the flat spring 70 can be reduced insize. The flat spring 70 is disposed to abut on the bobbin 54 and asurface of the flow passage block 27 closer to the opening end.

The tip portions 44 a on the driving portions 44 of the valve drivingmember 42 are defined as abutting portions which abut on the movableiron core 60. That is, the flat spring 70 applies its spring force tothe movable iron core 60. By this spring force, the swingable end of themovable iron core 60 presses the poppet valve 41 toward the first valveseat 24. Therefore, when the coil 56 has no driving current applied andis de-energized, as shown in FIG. 1, the magnetically-attracted surface64 is set to a state to separate from the magnetically-attractingsurface 63 by the spring force of the flat spring 70. The movable ironcore 60 presses the poppet valve 41 onto the first valve seat 24 throughthe valve driving member 42, against the spring force of the compressionspring 46. Thus, the communication between the first port 21 and thesecond port 22 is blocked.

In this manner, when the coil 56 is de-energized, the poppet valve 41 ispressed onto the first valve seat 24 and causes the valve driving member42 to be positioned at a lower limit where movements of the valvedriving member 42 are regulated. In this manner, abutting portions ofthe driving portions 44, that is, the tip portions 44 a, of the valvedriving member 42 serve as a fulcrum for a tensile force applied to themovable iron core 60; the engaging protrusion 76 serves as a “point ofeffort” of the tensile force; and the sliding-contacting surface 61serves as a “point of load”; whereby the flat spring 70 presses thesliding-contacting surface 61 onto the sliding-abutting surface 62.Thus, the sliding-contacting surface 61 is kept in a contacting statewith the sliding-abutting surface 62 even when the coil is de-energized,so that the sliding-contacting surface 61 is prevented from beingseparated from the sliding-abutting surface 62. In other words, the flatspring 70 functions to apply a spring force to the movable iron core 60in such a direction in which the magnetically-attracted surface 64separates from the magnetically-attracting surface 63, and a function tofix the sliding-contacting surface 61 onto the sliding-abutting surface62.

When the coil 56 is energized, a looped magnetic circuit is generatedbetween the fixed iron core 50 and the movable iron core 60 so that theswingable end of the movable iron core 60 is attracted toward thedriving leg 51, as shown in FIGS. 2 and 7. At this time, the movableiron core 60 exerts swinging movements against the spring force of theflat spring 70, while the sliding-contacting surface 61 slides on thesliding-abutting surface 62. During this swinging movement, a magneticflux flows between the arcuate sliding-contacting surface 61 and thesliding-abutting surface 62 to generate an attraction force; thus, themovable iron core 60 is prevented from being separated from thesupporting leg 52 of the fixed iron core 50. FIG. 8 shows the flowpassage block 27 illustrated by two-dot chain lines in order to clearlyindicate the contacting state between the valve driving member 42 andthe movable iron core 60.

Upon assembling the solenoid valve 10, the poppet valve 41 and thecompression spring 46 are preliminarily attached to the valve drivingmember 42. Next, the flow passage block 27 in which the valve drivingmember 42 has been assembled is inserted into the valve housing 11 fromthe opening end 17 so that the flow passage block 27 is attached to theflow passage portion 16 of the valve housing 11. The bobbin 54 ispreliminarily attached to the fixed iron core 50, and the coil 56 iswound around the bobbin 54. The movable iron core 60, the flat spring 70and the bobbin 54 which have been temporarily assembled by engagementsare then inserted into the valve housing 11 from the opening end 17. Themovable iron core 60 abuts on the tip portions 44 a of the valve drivingmember 42.

Since a bottom surface of the first flow passage forming portion 31 inthe flow passage block 27 is made in contact with the bottom portion ofthe valve housing 11, with the exception of the second port 22 and thevalve element housing hole 26, upper and lower positions of the flowpassage block 27 and the valve housing 11 are determined. Since theperipheral portion of the bottom surface of the flat spring 70 is madein contact with the upper surface of the flow passage block 27, theupper and lower positions of the flat spring 70 and the flow passageblock 27 are determined. Since bottom surfaces 96 and 97 of the fittingprotrusion 77 of the bobbin 54 are made in contact with a frame portion98 of the supporting portions 71 of the flat spring 70 and a frameportion 99 of the connected portion 74, the upper and lower positions ofthe bobbin 54 and the flat spring 70 are determined. Since the lowersurface of the yoke portion 53 of the fixed iron core 50 is made incontact with an upper surface of the abutting flange 57 of the bobbin54, the upper and lower positions of the fixed iron core 50 and thebobbin 54 are determined. In this manner, since the valve housing 11,the flow passage block 27, the flat spring 70, the bobbin 54 and thefixed iron core 50 have abutting surfaces which are made in contact withone another, the upper and lower positions are respectively determinedwhen these members are successively inserted into the valve housing 11.Thus, a temporarily assembled state is derived in which all parts to beinserted into the valve housing 11 are positioned and fixed.

The solenoid valve 10 has the valve housing 11 which is provided withthe flow passage portion 16 on its bottom portion; the poppet valve 41is disposed on the flow passage portion 16 of the valve housing 11, andparts such as the fixed iron core 50 and the movable iron core 60 whichdrive the poppet valve 41 are assembled into the solenoid valve 10. Inthis manner, the poppet valve 41 and members which drive the poppetvalve 41 are assembled in a single valve housing 11. Therefore, whencompared to a structure which has a member for storing the valve elementand a housing for storing parts which drive the valve element, thepresent invention can reduce the number of parts and further enhance theassembly workability of the solenoid valve 10.

The flow passage portion 16 is opened toward the opening end 17 of thevalve housing 11, and the housing space 18 in which members constitutingthe solenoid valve 10 are stored is opened in the opening end 17.Therefore, the solenoid valve 10 can be assembled by inserting all partswhich constitute the solenoid valve 10, such as the movable iron core60, from the opening end 17. The fixed iron core 50 and the coil 56 areattached to the bobbin 54. The fixed iron core 50 is engaged with andfixed to the engaging claw 75 on the flat spring 70, and the attachingclaws 72 of the flat spring is respectively engaged with and fixed tothe attaching claw holders 95 of the bobbin 54. In this manner, thefixed iron core 50, the coil 56, the bobbin 54, the flat spring 70 andthe movable iron core 60 are temporarily assembled as one integral unitbefore being inserted into the valve housing 11. The movable iron core60 is accurately positioned facing the fixed iron core 50 by theabutment between the arcuate sliding-abutting surface 62 and thesliding-contacting surface 61. Thus, the small-sized solenoid valve 10can be easily assembled.

In a state in which the fixed iron core 50 is inserted in the valvehousing 11, a liquid-state resin 84 is injected into and cured in thevalve housing 11. Thus, the fixed iron core 50 and bobbin 54 are fixedin the valve housing 11. The second sealing member 82 prevents theliquid-state resin 84, which is injected when assembling the solenoidvalve 10, to flow into the iron core housing chamber 59 through a gapformed between the fixed flange 58 of the bobbin 54 and the valvehousing 11. The second sealing member 82 further prevents theliquid-state resin 84 to flow into the iron core housing chamber 59through a gap formed between the supporting leg 52 and the fixed flange58.

A state prior to the injection of the liquid-state resin 84 into thevalve housing 11 corresponds to a temporarily assembled state of thesolenoid valve 10. Under this temporarily assembled state, all parts tobe assembled into the valve housing 11 are disposed at predeterminedpositions. Moreover, the gap between the fixed flange 58 and the valvehousing 11 is sealed by the first sealing member 81, the gap between thefixed flange 58 and the sealing flange 78 is sealed by the secondsealing member 82, and a gap between the yoke portion 53 and theabutting flange 57 is further sealed by the sealing member 83.Therefore, in a temporarily assembled state, characteristic inspectionsfor the solenoid valve 10 can be performed by activating the solenoidvalve 10, in which a driving current is applied to the coil 56 andcompressed air is supplied to the first port 21. During thecharacteristic inspection, if a predetermined operational characteristiccannot be obtained or if an operation failure occurs, parts such as thefixed iron core 50 which is attached with the coil 56 may be removedfrom the valve housing 11 so as to replace the defective part.Therefore, for example, if a defect is only in the coil 56, the fixediron core 50 can be reused, so that the manufacturing yield of thesolenoid valve 10 can be increased.

The compressed air supplied from the first port 21 or the like flowsinto the iron core housing chamber 59 via the through holes 45 andfurther flows into a gap between the driving leg 51 and the bobbin 54.However, the compressed air is hermetically sealed in by the sealingmember 83, and is prevented from leaking out from the valve housing 11.

A circuit board 85 is attached to the front wall 12 of the valve housing11. In order to support the circuit board 85, a plurality of circuitboard supporting claws 86 are provided on the front wall 12, and thecircuit board 85 is attached to the valve housing 11 by the circuitboard supporting claws 86. A conductive terminal 87 attached to theabutting flange 57 is connected to a winding wire of the coil 56, andwhen the circuit board 85 is attached to the front wall 12, theconductive terminal 87 is connected to a through hole provided on thecircuit board 85. A power-supply terminal 88 which supplies a drivingcurrent to the coil 56 from the outside is provided on the circuit board85.

As shown in FIGS. 1 and 2, an end cover 91 is detachably attached to theopening end 17 of the valve housing 11. A socket portion 92 to which aconnector (not shown) is attached, is provided on the end cover 91. Theconnector to be attached to the socket portion 92 is connected to thepower-supply terminal 88. A front cover 93 is attached to the front wall12 of the valve housing 11 and is covered over the circuit board 85.

When the solenoid valve 10 is operated in the temporarily assembledstate, the end cover 91 is not attached to the valve housing 11, and thefixed iron core 50 is pressed downward from the outside of the solenoidvalve 10. Thus, the assembly dimensions can be controlled as designed.Moreover, the compressed air prevents the internal parts of the solenoidvalve 10 from falling out of the solenoid valve 10.

In the solenoid valve 10, a side to which the circuit board 85 isattached is defined as a front side of the valve housing 11, an opposingside is defined as a rear side, and a portion where the ports 21 to 23are formed is defined as a bottom portion of the valve housing 11.Furthermore, a portion of the valve housing 11 to which the end cover 91is attached is defined as the opening end 17.

In a solenoid valve 10 used for pneumatic circuits which supplycompressed air from a compressed air-supply source to a pneumaticcylinder serving as an equipment to be supplied with compressed air, thefirst port 21 serves as an air-supply port which is connected to thecompressed air-supply source by an air-supplying pipe. The second port22 serves as an output port which supplies compressed air to thepressure chamber of the pneumatic cylinder, and the third port 23 servesas an exhaust port which discharges the compressed air which hadreturned from the pressure chamber. Therefore, when the coil 56 isde-energized, as shown in FIG. 1, the movable iron core 60 is driven bythe spring force of the flat spring 70 toward the valve driving member42 so that the poppet valve 41 abuts on the first valve seat 24. Thus,the poppet valve 41 is set at a closed position to block communicationbetween ports 21 and 22, and is further set at an open position to allowthe ports 22 and 23 to communicate with each other. In this state, airdischarged from the pressure chamber of the pneumatic cylinder isdischarged outside through the third port 23.

On the other hand, when the coil 56 is energized, as shown in FIG. 2,the movable iron core 60 is attracted toward the magnetically-attractingsurface 63 of the driving leg 51 against the spring force of the flatspring 70, and the magnetically-attracted surface 64 abuts on themagnetically-attracting surface 63. Thus, the poppet valve 41 is set ata closed position to block communication between the second port 22 andthe third port 23, and is further set at an open position to allow thefirst port 21 and the second port 22 to communicate with each other. Inthis state, compressed air is supplied to the pressure chamber of thepneumatic cylinder from the first port 21 through the second port 22.

When the ports 21 to 23 are allowed to communicate with a block-shapedmember, sealing members 94 are attached to the rear wall 13 at thebottom portion of the valve housing 11 in order to seal gaps between theblock-shaped member and the ports 21 to 23.

In a solenoid valve 10 described hereinafter, the above-mentionedthree-port solenoid valve is replaced with a two-port solenoid valve;the two-port solenoid valve has two ports 21 and 22, and a poppet valve41 can be operated between an open position to supply compressed airfrom the port 21 to a member to be supplied with compressed air, and aclosed position to block the supplying of the compressed air to themember; thus, the compressed air which is supplied to an equipment canbe controlled. In this case only one flow passage forming portion 31 isprovided on a flow passage block 27. In this variation, membersconstituting the solenoid valve 10 are inserted from an opening end 17,as is the case with the three-port solenoid valve; thus, the small-sizedsolenoid valve 10 can easily be assembled.

FIGS. 9 to 12 are cross-sectional views showing variations of thesolenoid valve 10. In these drawings, common members shown in theabove-mentioned solenoid valve 10 are indicated by the same referencenumbers.

In the solenoid valve 10 shown in FIGS. 9 and 10, each of the first tothird ports 21 to 23 extend in the longitudinal direction of a valvehousing 11, and are opened on a bottom surface of the valve housing 11.In this type of solenoid valve 10, a first port 21 is provided on avalve seat 24 and opened on a bottom surface of a valve element housinghole 26, and the second port 22 is also opened on the bottom surface ofthe valve element housing hole 26. A configuration for the ports 21 to23 as shown in FIGS. 1 and 2 is known as a “rear-ported type”, and FIG.9 shows a “bottom-ported type” configuration.

In the solenoid valve 10 shown in FIG. 11, a first port 21 and a secondport 22 are provided on a flow passage portion 16; however, the thirdport 23 as shown in FIGS. 1 and 2 is not provided. Therefore, thesolenoid valve is a two-port solenoid valve, and when a coil 56 has nodriving current applied and is de-energized, a poppet valve 41 abuts ona valve seat 24, as shown in FIG. 11, so that communication between thefirst port 21 and the second port 22 is blocked. On the other hand, whenthe coil 56 is energized, the poppet valve 41 separates from the valveseat 24 so that the first port 21 and the second port 22 are allowed tocommunicate with each other.

The solenoid valve 10 shown in FIG. 12 is a two-port solenoid valve inthe same manner as that of FIG. 11, and a first port 21 and a secondport 22 each extend in a longitudinal direction of a valve housing 11,the first port 21 and the second port 22 being provided on a bottomsurface of the valve housing 11. Therefore, the configuration for ports21 and 22 is “bottom-ported”.

The present invention is not limited to the above-mentioned embodiment,and is able to be variously modified in the range not departing from thesubstance.

The solenoid valve is applied to pneumatic circuits which suppliescompressed air to pneumatically operated equipment from a compressedair-supply source.

Although various embodiments of the present invention have beendescribed and shown, the invention is not restricted thereto, but mayalso be embodied in other ways within the scope of the subject-matterdefined in the following claims.

The invention claimed is:
 1. A solenoid valve comprising: a valvehousing having ports and in which a poppet valve is assembled; thepoppet valve being operated between a closed position in which thepoppet valve abuts on a valve seat to block communication among theports, and an open position in which the poppet valve separates from thevalve seat to enable communication among the ports; a fixed iron corewhich is assembled into the valve housing and is provided with: asupporting leg abutting on one end portion of a movable iron core whichdrives the poppet valve; a driving leg extending in parallel to thesupporting leg and abutting on the other end portion of the movable ironcore; and a yoke portion provided between a base end portion of thesupporting leg and a base end portion of the driving leg; the supportingleg, the driving leg, and the yoke portion being integrally formed witheach other; a coil provided on the fixed iron core; a sealing flange isprovided on a leading end portion of the supporting leg, the sealingflange being larger in depth than the supporting leg, and the supportingleg being equal in width to the sealing flange; and an abuttingprotrusion is formed on the supporting leg closer to the leading endportion than the sealing flange, and the sealing flange has a sealingsurface which surrounds the abutting protrusion.
 2. The solenoid valveaccording to claim 1, wherein the supporting leg is larger in width thanthe driving leg, and the yoke portion is equal in width to thesupporting leg.
 3. The solenoid valve according to claim 1, wherein theyoke portion has a sealing surface which surrounds the driving leg. 4.The solenoid valve according to claim 1, wherein the driving leg, thesupporting leg, and the yoke portion each has a quadrilateral shape incross-section.
 5. The solenoid valve according to claim 1, wherein thevalve housing has among the ports a first port and a second port, and aflow passage portion which is provided with a first valve seat having afirst communication hole through which the first port and the secondport communicate with each other; the valve housing further has a thirdport and a flow passage block which is provided with a second valve seathaving a second communication hole through which the second port and thethird port communicate with each other; and the poppet valve abuts onthe first valve seat to block communication between the first and secondports while the poppet valve separates from the second valve seat toallow the second and third ports to communicate with each other when thecoil is de-energized; and the poppet valve abuts on the second valveseat to block communication between the second port and the third portwhile the poppet valve separates from the first valve seat to allow thefirst and second ports to communicate with each other when the coil isenergized.
 6. The solenoid valve according to claim 1, wherein the fixediron core is provided with a bobbin having: a cylindrical main bodyaround which the coil is wound; an abutting flange provided on a baseend portion of the cylindrical main body and abutting on the yokeportion; a fixed flange provided on a leading end portion of thecylindrical main body and fixed into the valve housing; and a sealingmember is disposed between the abutting flange and the yoke portion. 7.The solenoid valve according to claim 6, wherein a first sealing memberis disposed between the fixed flange and the valve housing.
 8. Thesolenoid valve according to claim 7, wherein a second sealing member isdisposed between the fixed flange and the sealing flange provided on theleading end of the supporting leg.